Such material webs, which for example could be air-laid fibre webs, are generally produced continually in plants arranged in such a way that it is not possible to change the production rate of the plant during the winding-up process.
This fact is causing some problems in connection with roll shifting where the web is cut and a new winding-up operation is started on an empty roll shaft while the web at the same time continuously is supplied to the winding-up apparatus.
Problems also are arising at rupture of the web or when starting a new production of web as the supply of the web from the web producing plant to the winding-up apparatus in these cases does not take place in accordance with the usual winding-up cycles.
Many attempts have during the years been made for solving these problems. In these cases, the web roll being wound up is normally conveyed from a start position to a finish position for thereby making room for a new, empty roll shaft brought in position for winding-up a new web roll.
The best result is obtained when the winding-up of the web roll is carried out by means of a centre drive, directly rotating the roll shaft, in combination with a periphery drive, acting on the periphery of the web roll.
In a known winding-up apparatus, the winding-up operation is started with a centre drive which, when the web roll has reached a suitable size, is taken over or is supplemented by a periphery drive in form of a belt drive placed below the roll.
In another known winding-up apparatus the centre drive is taken over or is supplemented by a periphery drive in form of a drive roll acting on the periphery of the web roll.
These known winding-up apparatus suffer, however, of the drawback that it, at e.g. rupture of the web or starting of a new web production, is difficult and complicated to start the winding-up on a new, empty roll shaft as the apparatuses in such situations are not able to impart the necessary web tension to the web to cause the new roll shaft to catch the web. Neither is it possible manually to wrap the web around the old web roll for continuing the winding-up of the web on this roll.